Young people are starting to skip the very public postings of some of social media's original platforms. Why? And where will that leave the companies that rely on our willingness to divulge everything?

Thousands are taking to the Internet to petition for the freedom of convicted murderer Steven Avery.
Kirk Wagner/AP11 janvier 2016

The “like” is the predominant gesture on social media, whether you’re sticking to Facebook or shifting to Instagram. It may even be the most common gesture among humans nowadays. Some of us probably “like…